1. Field of the Invention
The present invention relates to an apparatus and method for manufacturing a jacketed antenna, and more particularly to an apparatus and method for manufacturing a mobile telephone antenna for motor vehicles that has electromagnetic wave receiving conductive parts centered in an encasing elastic nonconductive jacket.
2. Description of the Related Technology
Antennas, especially mobile telephone antennas for motor vehicles, are known. These antennas often include a base body from which a receiving portion extents, such as an antenna coil or an antenna rod. Further such base bodies are electrically conductive and can be made of metal with a contact area that is used to connect the antenna to a corresponding contact area on a motor vehicle by, for example, being screwed onto the motor vehicle body. Often the receiving portion of mobile antennas are elastic so that the mobile antennas are structurally compliant in the case of an accident and so that they can yield to wind forces. In addition to having elastic receiving portions, such mobile antennas often are surrounded with an electrically nonconductive jacket to protect encased metal parts from corrosion and to provide a smooth overall pleasant appearance for the mobile antenna structure.
It is known that such jacketed antenna structures can be manufactured by inserting an antenna base body with extending receiving portion into a mold and then filling the mold with the compound which forms the encasing jacket. A useful compound for the jacket can be a thermoplastic elastomer. It is important in this manufacturing process that the base body be centered when positioned in the mold because if one or more of the conductive antenna parts are not centered there is the possibility of not completely encasing them with the compound of the jacket. To address this problem, it has been suggested that the base body with the extending receiving portion be fixed in the mold with pins which extend in the direction of the lengthwise axis of the receiving portion. Such use of pins can position a base body with an extending receiving portion at a centered location in a mold. In doing so, however, there is an unavoidable problem in that holes are formed into the resulting jacket and moisture can penetrate through these holes into the interior of the antenna structure where metal corrosion can be produced that could lead to antenna malfunctions.